I've used Royal Purple, which stayed clean for the 3,000 miles, barely looked like it had run in the engine. I then tried Mobil 1 synthetic cause royal purple was about $6.00 a quart and it took 9 quarts to fill my pan and filter. I've read good things about the newest Mobil 1 synthetic which is supposed to be a generation ahead of everything else. Probably oil brand between the finer grades (Castrol, Valvoline, Mobile) is not that critical until the rings start wearing in a higher mileage car, plus wear on the bearings. something to consider is an oil cooler, as the warmer the oil, the less viscousity. It will help keep the engine running cooler and also help keep the oil from breaking down due to heat. I prefer synthetic or synthetic blend over the other. Also, I suggest avoiding the fast lube/oil change places like the plague. In some instances, the oil put into the cars is contaminated with water from the condensation in the underground tanks they use for oil storage. In other instances there is crud at the bottom of the tanks that can get sucked into the delivery system when the oil level in the storage tank is low, and that crud gets into your engine. I've read horror stories about this sort of thing.
My Chemical Engineer buddy in the lubrication business says 50% synthetic gives the benefit of full synthetic, that the longer chains (molecules) in synthetic lubricate much better, and last way longer since they hold up to heat much better than natural oil (molecules don't shorten and are very consistent). This explains the HP gains, and with a 50/50 mix it is easily worth the money to use it. Top off with regular oil between changes. 5000 miles no problem. 1 year storage, no problem for lesser driven cars.